Method for controlling stop operation of air conditioner

ABSTRACT

A method for controlling a stop operation of an air conditioner having a compressor, a four-way valve, an electronic expansion valve (EEV), an indoor fan and an outdoor fan includes the steps of stopping the operations of the compressor and the indoor fan if an operation stop signal is inputted during a heating operation; and checking an amount of elapsed time after the turn-offs of the compressor and the indoor fan, and turning off the EEV and the outdoor fan if the amount of elapsed time reaches a preset reference time. The methods also includes the steps of detecting pressures at an inlet side and at an outlet side of the compressor to calculate a pressure difference; and turning off the four-way valve if the calculated pressure difference reaches a preset reference pressure difference.

FIELD OF THE INVENTION

The present invention relates to an operation control method of an airconditioner, and specifically, to a stop operation control method of anair conditioner, which is suitable for controlling the stop operationbased on the inner environment (pressure or temperature) of an airconditioner at the time of stopping the air conditioner in a heatingoperation mode.

BACKGROUND OF THE INVENTION

As well-known in the art, a typical air conditioner has a structure asshown in FIG. 1 as one example.

Referring to FIG. 1, the typical air conditioner is largely divided intoan outdoor unit 110 and an indoor unit 120. The outdoor unit 110 isconstituted by a compressor 111, a four-way valve 112, an outdoor heatexchanger 113, an electronic expansion valve (EEV) 114, an accumulator115, an outdoor fan 116, and any other items obvious to one skilled inthe art for this application. The indoor unit 120 is constituted by anindoor heat exchanger 121, an indoor fan 123, and so forth.

During a cooling operation of the air conditioner with the typicalstructure described above, a high temperature, high pressure gaseousrefrigerant compressed in the compressor 111 is introduced, via thefour-way valve 112, into the outdoor heat exchanger 113 that functionsas a condenser. This high pressure gaseous refrigerant undergoes a heatexchange, through the outdoor heat exchanger 113, with outdoor air ofoutdoor temperature which is lower than the refrigerant temperature, tobe condensed to a high pressure state. Here, the outdoor fan 116 isdriven by an outdoor fan motor (not shown), and serves to forciblyventilate the outdoor air.

As the gaseous refrigerant condensed to high pressure passes through theEEV 114, it turns to low temperature, low pressure liquid refrigerant bythrottling, and is conveyed to the indoor heat exchanger 121 of theindoor unit 120. Here, the indoor fan 123 is driven by an indoor fanmotor (not shown), and serves to forcibly ventilate the indoor air.

Next, the refrigerant in a liquid state is evaporated through the heatexchange with indoor air at the indoor heat exchanger 121 functioning asan evaporator. After evaporation, the low temperature, low pressuregaseous refrigerant flows back to the outdoor unit 110 along acirculation line, in which it passes through the four-way valve 112 andis introduced again into the compressor 111 via the accumulator 115.Here, in the accumulator 115, the refrigerant having been introducedinto the compressor 111 changes completely into gas.

Moreover, during a heating operation of the air conditioner with thetypical structure described above, the direction of the refrigerant atthe four-way valve 112 is reversed, thus, the refrigerant flows inopposite direction from the refrigerant flow during the coolingoperation mentioned above. At this time, since the indoor heat exchanger121 functions as a condenser differently from the cooling operation,warm air is circulated again into the indoor environment by the indoorfan 123. That is, the refrigerant flow during the heating operation ofthe air conditioner follows the circulation line, such as, thecompressor 111->the four-way valve 112->the indoor heat exchanger121->the EEV 114->the outdoor heat exchanger 113->the four-way valve112->the accumulator 115->the compressor 111.

Meanwhile, the air conditioner with the refrigerant circulation linedescribed above is set up in such a way that the position of thefour-way valve automatically returns to a position for cooling operationif the air conditioner that had been in heating mode stops running.

As well-known in the art, when the air conditioner is in the heatingmode, the inlet side of the compressor is at a relatively low pressurestate, while the outlet side of the compressor is at a relatively highpressure state. If the air conditioner stops running in the heatingmode, the pressure at the inlet side of the compressor slowly increases,while the pressure at the outlet side of the compressor slowlydecreases, so that those pressures at the inlet and outlet sides of thecompressor become gradually equalized for a long stretch of time.

Therefore, it is necessary to equalize the pressures on both sides(i.e., the inlet and the outlet) of the compressor more quickly. Aconventional way to control the stop operation of an air conditioner wasthat when an operating stop signal is inputted in the middle of theheating operation, the compressor and the indoor fan were first turnedoff together, and the EEV, the outdoor fan and the four-way valve arealso turned off after a specified amount of time has passed.

However, the simultaneous turn-offs of the EEV, the outdoor fan and thefour-way valve as in the conventional way for the purpose of pressureequalization between the inlet side and the outlet side of thecompressor could not resolve the problem completely because there wasstill a pressure difference above a certain level between the inlet sideand the outlet side of the compressor. Consequently, when the four-wayvalve automatically returns to the position for cooling operation, animpact noise that sounds like “shook” is generated. This noise problemis now at issue as customer complains.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a methodfor controlling a stop operation of an air conditioner, capable ofpreventing an impact noise at a four-way valve due to a difference inpressure that occurs when the four-way valve automatically returns to aposition for cooling operation after a heating operation of the airconditioner stops.

In accordance with one aspect of the invention, there is provided amethod for controlling a stop operation of an air conditioner having acompressor, a four-way valve, an electronic expansion valve (EEV), anindoor fan and an outdoor fan, the method including the steps of:turning off the compressor and the indoor fan if an operation stopsignal is issued during a heating operation of the air conditioner;checking an amount of elapsed time and turning off the EVV and theoutdoor fan if an amount of elapsed time after the turn-offs of thecompressor and the indoor fan reaches a preset reference time; detectingpressures at an inlet side and at an outlet side of the compressor tocalculate a pressure difference therebetween; and turning off thefour-way valve if the calculated pressure difference reaches a presetreference pressure difference.

It is preferable that the preset reference pressure difference is about3 mb.

In accordance with another aspect of the invention, there is provided amethod for controlling a stop operation of an air conditioner includinga condenser and an evaporator in a structure that a compressor, afour-way valve, an EEV, an indoor fan and an outdoor fan are physicallyconnected to one another, the method including the steps of: turning offof the compressor and the indoor fan if an operation stop signal isissued during a heating operation of the air conditioner; turning off ofthe EVV and the outdoor fan, if the amount of elapsed time after theturn-offs of the compressor and the indoor fan reaches a presetreference time; detecting temperatures at the condenser and at theevaporator to calculate a temperature difference therebetween; andturning off of the four-way valve if the calculated temperaturedifference reaches a preset reference temperature difference.

It is preferable that the preset reference temperature difference isabout 10° C.

In accordance with another aspect of the invention, there is provided anair conditioner capable of preventing an impact noise generated afterthe completion of a heating operation of the air conditioner, whichcomprises: a compressor; a four-way valve; an electronic expansionvalve; an indoor fan; an outdoor fan; a first and a second pressuresensors for detecting pressures at an inlet side and at an outlet sideof the compressor, respectively; and a controller for turning off thecompressor and the indoor fan, turning off the electronic expansionvalve and the outdoor fan in a preset reference time after the turn-offsof the compressor and the indoor fan, and turning off the four-way valveif the pressure difference between the inlet side and the outlet side ofthe compressor reaches a preset reference pressure difference.

In accordance with still another aspect of the invention, there isprovided an air conditioner capable of preventing an impact noisegenerated after the completion of a heating operation of the airconditioner, which includes: a compressor; a four-way valve; anelectronic expansion valve; an indoor fan; an outdoor fan; a condenser;an evaporator; a first and a second temperature sensors for detectingtemperatures at the condenser and at the evaporator, respectively; and acontroller for turning off the compressor and the indoor fan, turningoff the EEV and the outdoor fan, and turning off the four-way valve ifthe temperature difference between the condenser and the evaporatorreaches a preset reference temperature difference.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention willbecome apparent from the following description of preferred embodiments,given in conjunction with the accompanying drawings, in which:

FIG. 1 shows an overall structural view of a typical air conditionersystem;

FIG. 2 illustrates a block diagram of an operation control apparatus ofan air conditioner suitable for application of a method for controllinga stop operation of an air conditioner in accordance with a preferredembodiment of the present invention;

FIG. 3 provides a flowchart describing a procedure for the stopoperation control of an air conditioner in accordance with a preferredembodiment of the present invention;

FIG. 4 illustrates a block diagram of an operation control apparatus ofan air conditioner suitable for application of a method for controllinga stop operation of an air conditioner in accordance with anotherpreferred embodiment of the present invention;

FIG. 5 offers a flowchart describing a procedure for the stop operationcontrol of an air conditioner in accordance with another preferredembodiment of the present invention; and

FIG. 6 presents an example of a timing chart illustrating a procedure ofstop operation control during a heating operation in accordance with thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following description of the preferred embodiment, reference ismade to accompanying drawings that form a part hereof and in which isshown by way of illustration a specific embodiment in which theinvention may be practiced. It is to be understood that otherembodiments may be utilized and structural changes may be made withoutdeparting from the scope of the present invention.

Unlike the above-described conventional method for the stop operationcontrol of an air conditioner in a heating mode which simultaneouslyturns off a compressor and an indoor fan first, and also turns off anEEV, an outdoor fan and a four-way valve after a specified amount oftime elapses, in accordance with the technical gist of the presentinvention, in the present invention the compressor and the indoor fanare first turned off at the same time and the EEV and the outdoor fanare simultaneously turned off after a specified amount of time haspassed. That is, in order to more easily accomplish the stop operationcontrol of an air conditioner during the heating operation, the presentinvention suggests that a pressure difference between the inlet side andthe outlet side of the compressor, or a temperature difference between acondenser and an evaporator should be detected after the simultaneousturn-offs of the EEV and the outdoor fan, and a turn-off time of thefour-way valve should be decided based on the detection result (i.e.,the pressure difference or the temperature difference).

First Embodiment

FIG. 2 is a schematic block diagram of an operation control apparatus ofan air conditioner suitable for application of a method for controllinga stop operation of an air conditioner in accordance with one embodimentof the present invention. The operation control apparatus of an airconditioner includes an operating block 202, a first pressure sensor204, a second pressure sensor 206, a control block 208, a compressordriving block 210, an EEV driving block 212, an indoor fan driving block214, an outdoor fan driving block 216, and a four-way valve drivingblock 218.

Referring to FIG. 2, the operating block 202 is provided with aplurality of operation keys which allow a user to select the operationinformation of an air conditioner, such as power-on, operation mode(cooling operation mode, heating operation mode, etc.), specifiedtemperature, air volume and the like. Various operation informationgenerated by user input is forwarded to the control block 208.

The first pressure sensor 204 is installed at a designated position ofthe inlet side of a compressor 111 inside an outdoor unit 110 shown inFIG. 1 as one example, and detects pressure at the inlet side of thecompressor. A pressure value detected at the inlet side of thecompressor is sent to the control block 208 for the stop operationcontrol under a heating operation in accordance with the presentinvention.

Likewise, the second pressure sensor 206 is installed at a designatedposition of the outlet side of a compressor 111 inside an outdoor unit110 shown in FIG. 1 as one example, and detects pressure at the outletside of the compressor. A pressure value detected at the outlet side ofthe compressor is delivered to the control block 208 for the stopoperation control under a heating operation in accordance with thepresent invention.

The control block 208 includes, for example, a microprocessor, or anyother device obvious to one skilled in the art for carrying out thesimilar task, so as to carry out the overall operational control of theair conditioner, which performs the control of the stop operation (timelag OFF control of a compressor, an indoor fan, an EEV, and an outdoorfan) when the air conditioner performs a heating operation, and the OFFcontrol of the four-way valve based on a pressure difference between theinlet side and the outlet side of the compressor, and so on. Moredetails will be provided later in reference to FIG. 3.

The compressor driving block 210 has functions for the ON/OFF control ofthe compressor 111, and the operation control of the compressor 111 at aspecified operating frequency, and so on, which is in response to acompressor drive control signal that is provided from the control block208. The EEV driving block 212 has functions for the adjustment ofdivergence of the EEV 114 shown in FIG. 1, and so on, in response to adivergence control signal that is also provided from the control block208.

In addition, the indoor fan driving block 214 has a function for theoperation control of the indoor fan 123 shown in FIG. 1, in response toan indoor fan drive control signal that is provided from the controlblock 208. The outdoor fan driving block 216 has a function for theoperation control of the outdoor fan 116 shown in FIG. 1, in response toan outdoor fan drive control signal that is provided from the controlblock 208. Lastly, the four-way valve driving block 218 has a functionfor the operation control of the four-way valve 112 shown in FIG. 1, inresponse to a four-way valve drive control signal that is provided fromthe control block 208.

The following is a description for a stepwise procedure which carriesout the stop operation control of an air conditioner according to thepresent invention using an operation control apparatus of the airconditioner having the above-described constitution.

FIG. 3 is a flowchart describing a procedure for the stop operationcontrol of an air conditioner in accordance with an embodiment of thepresent invention.

Referring to FIG. 3, when the air conditioner is running in a heatingmode according to operating conditions set by a user at step S302, thecontrol block 208 checks at step S304 whether an operation stop signalaccording to user input has been received from the operating block 202.

In step S304, if the operation stop signal is received, the controlblock 208 generates a control signal for turning off the compressor 111and a control signal for turning off the indoor fan 123 at the sametime, and transfers the signals to the compressor driving block 210 andthe indoor fan driving block 214, respectively. Consequently, thecompressor 111 and the indoor fan 123 are turned off (or stop running)under the control of the compressor driving block 210 and the indoor fandriving block 214 at step S306.

Next, the control block 208 counts an elapsed time after the turn-off ofthe compressor 111, by using its internal timer (not shown), to checkduring step S308 if the elapsed time t1 has reached a preset referencetime n1 (e.g., 1 minute).

In step S308, if the elapsed time t1 has reached a preset reference timen1, the control block 208 simultaneously generates control signals forturning off the EEV 114 and the outdoor fan 116, and transfers them tothe EEV driving block 212 and the outdoor fan driving block 216,respectively. Consequently, the EEV 114 and the outdoor fan 116 stoprunning under the control of the EEV driving block 212 and the outdoorfan driving block 216 at step S310.

Thereafter, the control block 208 calculates a pressure differencebetween a pressure value at the inlet side of the compressor 111detected which is provided by the first pressure sensor 204 and apressure value at the outlet side of the compressor 111 detected whichis provided by the second pressure sensor 206 at step S312, and comparesthe calculated pressure difference with a preset reference pressuredifference (e.g., 3 mb), to thereby check at step S314 whether thecalculated pressure difference has reached the reference pressuredifference.

Here, it would be most ideal to equalize the pressures at the inlet andoutlet sides of the compressor. In such a case, however, it takes toomuch time to get the pressure equalization at both sides. Taking thisproblem into consideration, the present invention suggests that thefour-way valve should be turned off when the pressure difference betweenthe inlet side and the outlet side of the compressor is about 3 mb.

In step S314, if the calculated pressure difference has reached thepreset reference pressure difference, the control block 208 generates acorresponding control signal for turning off the four-way valve, anddelivers the same to the four-way valve driving block 218. Consequently,the four-way valve 112 is turned off under the control of the four-wayvalve driving block 218, and thus, the heating operation of the airconditioner finally ends at step S316.

FIG. 6 shows an example of a timing chart illustrating the procedure ofa stop operation control during the heating operation in accordance withthe present invention. It is evident from the timing chart that thefour-way valve is turned off after a preset amount of time (that is, atthe time a pressure difference at the inlet side and the outlet side ofthe compressor has reached the preset reference pressure difference) haspassed from the simultaneous turn-offs of the EEV and the outdoor fan.

To be short, unlike the conventional method for the stop operationcontrol of an air conditioner in the heating mode which involvessimultaneous turn-offs of an EEV, an outdoor fan, and a four-way valve,according to the method for the stop operation control of an airconditioner in accordance with the embodiment, the EEV and the outdoorfan are first turned off, and the four-way valve is then turned off onlyif a pressure difference at the inlet side and the outlet side of acompressor reaches a preset level (reference pressure difference). Inthis way, it becomes possible to effectively prevent an impact noise atthe four-way valve due to the pressure difference caused when thefour-way valve automatically returns to a position for cooling operationafter the heating operation of an air conditioner stops.

Second Embodiment

FIG. 4 is a block diagram of an operation control apparatus of an airconditioner suitable for application of a method for controlling a stopoperation of an air conditioner in accordance with another embodiment ofthe present invention. This invention operation control apparatusincludes an operating block 402, a first temperature sensor 404, asecond temperature sensor 406, a control block 408, a compressor drivingblock 410, an EEV driving block 412, an indoor fan driving block 414, anoutdoor fan driving block 416, a four-way valve driving block 418 andthe like.

Referring to FIG. 4, the components of the operation control apparatusof the second embodiment of the invention are substantially identical tothose of the first embodiment shown in FIG. 2 in structure except thatthe second embodiment employs the first and the second temperaturesensors 404 and 406, instead of the first and the second pressuresensors 204 and 206 used in the first embodiment. Thus, in order toavoid any redundant, repetitive description unnecessary for simplicityof the specification, details on functions of the same components withsubstantially identical functions will be omitted here.

Specifically, the first temperature sensor 404 is installed at, forexample, a specified position of a pipe at a condenser side, and detectsa temperature at the condenser side (that is, a temperature during thestop operation control). The temperature value detected at the condenserside is then sent to the control block 408 for the stop operationcontrol in the heating mode according to the present invention.

Likewise, the second temperature sensor 406 is installed at, forexample, a specified position of a pipe at an evaporator side, anddetects a temperature at the evaporator side (that is, a temperatureduring the stop operation control). A temperature value detected at theevaporator side is then fed to the control block 408 for the stopoperation control in the heating mode in accordance with the presentinvention.

Then, the control block 408 performs an operational control of thefour-way valve in the stop mode based on a temperature difference at thecondenser side and at the evaporator side, which is derived from thetemperatures detected and provided by the first and the secondtemperature sensors 404 and 406. Further details on this controlprocedure will be provided below with reference to FIG. 5.

FIG. 5 is a flowchart describing the procedure for the stop operationcontrol of an air conditioner in accordance with another embodiment ofthe present invention.

Referring to FIG. 5, steps from S502 to S510 (the figures do notcorrespond with figure numbers) in the procedure are substantiallyidentical to steps S302 to S310 of FIG. 3 illustrated as the firstembodiment. Therefore, to avoid any redundant, repetitive descriptionunnecessary for simplicity of the specification, details on those stepswill be omitted here.

At step S512, the compressor 111 and the indoor fan 123 are first turnedoff in response to an operation stop signal, and the EEV 114 and theoutdoor fan 116 are also turned off after a preset time interval. Then,the first and the second temperature sensors 404 and 406 detect atemperature in the pipe at the condenser side and a temperature in thepipe at the evaporator side, respectively, and provide them to thecontrol block 408. With these temperatures, the control block 408calculates a temperature difference at the condenser side and at theevaporator side.

For instance, when an air conditioner is in a heating operation mode,the temperature at the condenser side usually ranges from about 40 to44° C., and the temperature at the evaporator side ranges from about 12to 18° C.

At a next step S514, the control block 408 compares a calculatedtemperature difference with a preset reference temperature difference(e.g., 10° C.), to check whether the calculated temperature differencehas reached the reference temperature difference.

Although it would be most ideal to make the temperatures at thecondenser side and at the evaporator side equalized, it would takes toomuch time. Taking this problem into consideration, the present inventionsuggests that the four-way valve should be turned off when thetemperature difference between the condenser side and the evaporatorside is around 10° C.

In step S514, if the calculated temperature difference has reached thepreset reference temperature difference, the control block 408 generatesa corresponding control signal for turning off the four-way valve, anddelivers it to the four-way valve driving block 418. Consequently, thefour-way valve 112 is turned off under the control of the four-way valvedriving block 418, so that the heating operation of the air conditionerfinally ends at step S516.

Even though the stop operation control method of this embodiment differsfrom the first embodiment in that a temperature difference at thecondenser side and at the evaporator side is utilized, and not apressures difference at the inlet and outlet sides of the compressor,both methods practically provide the same effects of impact noiseprevention at the four-way valve due to a pressure difference thatoccurs when the four-way valve automatically returns to a position forcooling operation after the heating operation of an air conditionerstops.

As described above, unlike the above-described conventional method forthe stop operation control of an air conditioner in a heating mode whichsimultaneously turns off a compressor and an indoor fan first, and alsoturns off an EEV, an outdoor fan and a four-way valve after a set amountof time elapses, according to the technical gist of the presentinvention, the compressor and the indoor fan are first turned off at thesame time and the EEV and the outdoor fan are simultaneously turned offafter a set amount of time has passed. That is, to more easilyaccomplish the stop operation control of an air conditioner during theheating operation, the present invention suggests that a pressuredifference between the inlet side and the outlet side of the compressor,or a temperature difference between a condenser and an evaporator shouldbe detected after the simultaneous turn-offs of the EEV and the outdoorfan, and a turn-off time of the four-way valve should be decided basedon the detection result (i.e., the pressure difference or thetemperature difference). As a result, the present invention can preventan impact noise at the four-way valve due to a pressure difference thatoccurs when the four-way valve automatically returns to a position forcooling operation after the heating operation of an air conditionerstops.

While the invention has been shown and described with respect to thepreferred embodiments, it will be understood by those skilled in the artthat various changes and modification may be made without departing fromthe spirit and scope of the invention as defined in the followingclaims.

1. A method for controlling a stop operation of an air conditionerhaving a compressor, a four-way valve, an electronic expansion valve(EEV), an indoor fan and an outdoor fan, the method comprising the stepsof: turning off the compressor and the indoor fan if an operation stopsignal is issued during a heating operation of the air conditioner;checking an amount of elapsed time and turning off the EEV and theoutdoor fan if an amount of elapsed time after the turn-offs of thecompressor and the indoor fan reaches a preset reference time; detectingpressures at an inlet side and at an outlet side of the compressor tocalculate a pressure difference therebetween; and turning off thefour-way valve if the calculated pressure difference reaches a presetreference pressure difference.
 2. The method of claim 1, wherein thepreset reference pressure difference is about 3 mb.
 3. A method forcontrolling a stop operation of an air conditioner including a condenserand an evaporator in a structure that a compressor, a four-way valve, anEEV, an indoor fan and an outdoor fan are physically connected to oneanother, the method comprising the steps of: turning off of thecompressor and the indoor fan if an operation stop signal is issuedduring a heating operation of the air conditioner; turning off the EEVand the outdoor fan, if the amount of elapsed time after the turn-offsof the compressor and the indoor fan reaches a preset reference time;detecting temperatures at the condenser and at the evaporator tocalculate a temperature difference therebetween; and turning off thefour-way valve if the calculated temperature difference reaches a presetreference temperature difference.
 4. The method of claim 4, wherein thepreset reference temperature difference is about 10° C.
 5. An airconditioner capable of preventing an impact noise generated after thecompletion of a heating operation of the air conditioner, whichcomprises: a compressor; a four-way valve; an electronic expansionvalve; an indoor fan; an outdoor fan; a first and a second pressuresensors for detecting pressures at an inlet side and at an outlet sideof the compressor, respectively; and a controller for turning off thecompressor and the indoor fan, turning off the electronic expansionvalve and the outdoor fan in a preset reference time after the turn-offsof the compressor and the indoor fan, and turning off the four-way valveif the pressure difference between the inlet side and the outlet side ofthe compressor reaches a preset reference pressure difference.
 6. Theair conditioner of claim 7, wherein the preset reference pressure isabout 3 mb.
 7. An air conditioner capable of preventing an impact noisegenerated after the completion of a heating operation of the airconditioner, which comprises: a compressor; a four-way valve; anelectronic expansion valve; an indoor fan; an outdoor fan; a condenser;an evaporator; a first and a second temperature sensors for detectingtemperatures at the condenser and at the evaporator, respectively; and acontroller for turning off the compressor and the indoor fan, turningoff the EEV and the outdoor fan in a preset reference time after theturn-offs of the compressor and the indoor fan, and turning off thefour-way valve if the temperature difference between the condenser andthe evaporator reaches a preset reference temperature difference.
 8. Theair conditioner of claim 10, wherein the preset reference temperaturedifference is about 10° C.